Titanium in metallic form or as a compound is an important element in the chemical series. For example, titanium dioxide is utilized in paint pigments, in white rubbers and plastics, floor coverings, glassware and ceramics, painting inks, as an opacifying agent in papers, etc. The other titanium compounds are used in electronics, as fire retardants, waterproofing agents, etc. The metal may be used as such or in alloy form as structural material in aircraft, in jet engines, marine equipment, textile machinery, surgical instruments, orthopedic appliances, sporting equipment, food handling equipment, etc. Heretofore in recovering the titanium from titanium bearing sources such as ilmenite, rutile, etc., the titanium has been subjected to separation steps which involve the formation of titanium as a compound in a valence state of +4, such compounds usually involving titanium oxide. However, when attempting to separate titanium dioxide from impurities which are also contained in the ore such as iron, the hydrolysis of the titanium dioxide at elevated temperatures from solutions containing soluble titanium species usually results in also obtaining relatively large amounts of iron impurity with the titanium dioxide product.
Heretofore in the prior art various methods have been utilized to recover titanium values from titanium bearing sources. For example, in U.S. Pat. No. 3,236,596 an unroasted ilmenite ore is leached with hydrogen chloride at an elevated temperature. Following this, dissolved iron is reduced with iron or other reductants to precipitate ferrous chloride by saturating the liquor with hydrogen chloride gas. The hydrogen chloride is then extracted from the liquor by a vacuum distillation and the titanium is recovered by conventional means. Likewise, U.S. Pat. No. 3,825,419 reduces an ilmenite ore to produce ferrous oxides. The reduced ore is then leached for about 4 hours under a moderate pressure thereby dissolving the iron in the acid along with about 15% of the titanium. The iron is recovered as ferric oxide containing impurities in the spray roaster while the insoluble product which is primarily titanium dioxide but which contains all of the silica present in the original ore is recovered. U.S. Pat. No. 3,859,077 also discloses a process for recovering titanium in which a titanium tetrahalide is mixed with iron oxide in slag or a titaniferous ore at an extremely high temperature of about 1000.degree. C. to produce volatile impurity chlorides and titanium dioxide. A similar patent, U.S. Pat. No. 3,929,962 also reduces a titanium bearing ore at a high temperature to produce titanium sesquioxide which is in a form whereby it is easier to treat for a titanium-iron separation. Another prior art reference, U.S. Pat. No. 3,903,239 teaches a method for recovering titanium in which unroasted ilmenite is leached over a period of days at room temperature to recover about 80% of the titanium. Sulfur dioxide is added after the leaching to cause a precipitation of the ferrous chloride after which titanium dioxide is recovered by diluting and heating the solution. While the magnetic susceptibility of ilmenite has been known to change by subjecting the ilmenite to a high temperature roast, I have now discovered that by utilizing the process hereinafter set forth in greater detail it will be possible to insure complete conversion of the ilmenite to a magnetic material which then may be separated from non-magnetic rutile and recycled for further treatment. By utilizing the method of the present invention it will be possible to obtain a conversion of the raw ore to the desired titanium metal values thereby permitting the production of said titanium metal values in an economically feasible manner.
This invention relates to a process for separating rutile from ilmenite. More specifically, the invention is concerned with the process for recovering greater yields of titanium from a titanium bearing source such as ilmenite thus insuring the obtention of said titanium in an economically feasible manner. By utilizing the improvement herein described in a process for obtaining titanium from a titanium bearing source, it is possible to obtain greater yields of the desired product with a separation of magnetic material from non-magnetic material whereby the former may be recycled for further separation steps.
It is therefore an object of this invention to provide an improved process for the production of titanium metal values.
A further object of this invention is to provide an improvement in a process for separating a titanium metal value such as rutile from a titanium bearing source such as ilmenite in a more economical and commercially feasible manner.
In one aspect an embodiment of this invention resides in a process for the separation of rutile and ilmenite from ilmenite leach tails which comprises subjecting said leach tails to a flotation treatment to separate gangue from said leach tails, subjecting the separated leach tails to a roast at an elevated temperature in a hydrous atmosphere whereby said ilmenite is rendered magnetic in nature, and separating the non-magnetic rutile from the magnetic ilmenite.
A specific embodiment of this invention is found in a process for the separation of rutile and ilmenite from ilmenite leach tails which comprises subjecting said leach tails to a flotation treatment to separate gangue from said leach tails, thereafter subjecting the separated leach tails to a roast at a temperature in the range of from about 700.degree. to about 1000.degree. C. in a hydrous atmosphere which is afforded by the presence of steam whereby said ilmenite is rendered magnetic in nature and thereafter separating the non-magnetic rutile from the magnetic ilmenite.